I've done some quick test.
Specimen is one of my Extron MDV3.Instruments used were
TruePosition based GPSDO producing 10MHz at 11.9dBmHP8644A producing 15MHz at
10dBmHP8591EM spectrum analyzer
HP437B power meter + 482A sensor
I connected 10MHz to OUTPUT port of Extron MDV3. Nothing was detected on input
or other output ports. Non detectable either by power meter or SpecAn.I
connected 10MHz to OUTPUT port and looked at other OUTPUT port. Nothing
detected as well.
I connected 10MHz to INPUT port and took a power measurement at output port of
Extron. 11.2dBmI connected 10MHz to INPUT port and looked at output port by
SpecAn. Keeping eyes on CRT
Then I connected 15MHz to OUTPUT port, zero change on CRT
As far as Saturation, up to 12.3dBm input, it was clean. Above this, 2nd
harmonic started to show up. At 14dBm, all harmonics were -40dB below the
primary signal. This is probably the limit I'd go.
With this, I can conclude this particular device has a "pretty good" isolation
between output port and output to input port, as well as sufficient protection
for reverse leakage. Obviously, my result is specific to my device. Some
future/past design revision, other models, other makes, etc has to be
re-measured.
I left test setup as-is. If anyone want me to test something else, I'd be
happy to.
---------------------------------------
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
On Saturday, October 19, 2019, 2:02:32 PM EDT, tim...@timeok.it
<tim...@timeok.it> wrote:
Hi,
A premise must be made to define the performance of these DAs as EXTRON can
be compared to those built for the distribution of reference frequencies.
The Extron is a very nice solution, certainly of modest price, but we must
consider that its performances are limited. This especially if we talk about
saturation levels but much more important is the low separation between the
output channels. These two factors can be negligible if the required
level/stability is good but not excellent, in fact by disconnecting a load or
simply changing the length of a coax connection on a channel almost certainly a
change in level / phase will occur in the adjacent output.
If anyone is interested, you will find my solution here:
http://www.timeok.it/wp-content/uploads/2015/08/Frequency-Distribution-Design-Basic-Module-v-4.1.pdf
Using it as a buffer for the low phase noise HP 10811-60109 and BVA 8600
there is no deterioration of the phase / noise floor.
I ordered some new PCBs related to the buffer only. If anyone is interested
let me know off list.
Luciano
tim...@timeok.it
Da "time-nuts" time-nuts-boun...@lists.febo.com
A "Discussion of precise time and frequency measurement"
time-nuts@lists.febo.com
Cc
Data Sat, 19 Oct 2019 08:30:02 +0000
Oggetto Re: [time-nuts] Using commercial video amplifier for 10MHz clock
distribution.
There is a schematic here on the Extron uploaded by a TN member. The
schematic for the Extron looks looks dead simple that one could really just
make a simple 3 channel with the included mods in the writeup, only problem is
I don't see a source for a CLC409 any longer, and I don't have the experience
or knowledge to use a substitute ADA800x ??
<http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Extron_ADA_6_modifications_for_use_as_10MHz_distribution_amp_STEINMETZ.pdf>
-=Bryan=-
________________________________
From: time-nuts <time-nuts-boun...@lists.febo.com> on behalf of ed breya
<e...@telight.com>
Sent: October 18, 2019 1:39 PM
To: time-nuts@lists.febo.com <time-nuts@lists.febo.com>
Subject: Re: [time-nuts] Using commercial video amplifier for 10MHz clock
distribution.
I have a Hitachi VD-1000 video distribution unit that's been sitting
unused for years, waiting until I finally get around to making it into a
reference unit. I just dug it out and looked inside. It is full of RCA
jack cables for jumping the signals around in different ways. I
apparently had changed things around already, to make one section into a
15-output distributor. I have forgotten all about it long ago, so now
it's just a dizzying array of cabling. I must have made notes somewhere,
that I'll have to find for when I eventually (probably fairly soon) do
the proper conversion.
It uses CLC404 amplifiers, which appear to be older and a little noisier
than the CLC409, but should be OK for this. Unfortunately, it uses a
small switching supply, which I dislike for things like this, so
ultimately will make a linear one for it.
This thing has 40 BNC connectors on the back, which would allow for lots
of I/O and branching combinations. This is likely way more than I'll
ever need, so the "new" plan is to incorporate some improvements,
considering what I recently learned during my work on the frequency
multiplier project. I'll be reducing the total fanout, and changing some
of the outputs to have fully-floating transformer coupling, to reduce
ground loop effects in high sensitivity applications, and also
independent volume controls for some. I may do the same on the source
inputs too. I don't know how many of each thing yet, but definitely
some. In any of the BNC spots, I can easily put an isolating type BNC,
or a volume control pot. The front panel is mostly blank, so there's
lots of room for even more stuff there. I just have to be careful to not
get carried away and make it too wonderful and complicated and never
finished.
I also have an Efratom something-something distribution rack with five
"MBF" modules that have four outputs each. They should pretty good too,
but unfortunately it's all for 5 MHz only - there's low- or band-pass
filtering built into each channel, so needs reverse engineering and mods
for 10 MHz. I vaguely recall looking for info on this about a year ago,
and stumbled upon an old time nuts thread. Someone (maybe Chuck Harris?)
had reported successful mods for 10 MHz on these, but there were no
links to any info about it. So Chuck, if you see this, and it was you,
or anyone else, I'd sure appreciate this info. If it was just my
imagination, then never mind.
Ed
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